Bayesian Nash Equilibrium, Microeconomics

Consider 2 firms i=1,2 producing quantities q1 and q2 respectively. Let the market price be given by P=a-b(q1+q2). Firm 1''s Marginal cost c is common knowledge but 2''s cost is not known to 1 it is c+s where s is contained in (-a,a) with a distribution F(.) and E(s)=0. If s<0 firm 2 is more efficient than firm 1 and if s>0 firm 2 is less efficient than firm 1. Find the Bayesian Nash Equilibrium